Active substances/preparations of active substances formulated in aqueous solutions are to some extent subject to instabilities that may lead to reduced efficacy or bioactivity and elevated toxicity or incompatibilities. This applies to both conventional pharmaceuticals and peptide- or protein-containing active substances. The stability of pharmaceutical active substances can be positively affected through modification of the structure (internal) or through the addition of suitable adjuvants (external).
A conventional process for external stabilization of pharmaceutical active substances is the application of suitable adjuvants. Adjuvants that stabilize active substances can be broadly classified into: sugars and polyols, amino acids, amines, salts, polymers, and tensides.
Sugars and polyols are often used as unspecific stabilizers. Their stabilizing effect on biological active substances is chiefly ascribed to “preferential exclusion” (Xie and Timasheff, 1997, Biophysical Chemistry 64(1-3), 25-43; Xie and Timasheff, 1997, Protein Science, 6(1), 211-221; Timasheff, 1998, Advances in Protein Chemistry, 51, 355-432). During the selection of sugars, reducing sugars are mostly avoided for biological active substances. Saccharose and trehalose as non-reducing sugars are preferably used. Other examples of suitable adjuvants are glucose, sorbitol, glycerol (Boctor and Mehta, 1992, Journal of Pharmacy and Pharmacology, 44 (7), 600-3; Timasheff, 1993, Annual Review of Biophysics and Biomolecular Structure, 22, 67-97; Chang et al., 1993, Pharmaceutical Research, 10(10), 1478-83), and Mannitol (Hermann et al., 1996, Pharmaceutical Biotechnology, 9 (Formulation, Characterization, and Stability of Protein Drugs) 303-328; Chang et al., 1996, Pharmaceutical Research, 13(5), 756-761). Also known is the stabilizing effect that a wide variety of polymers have on pharmaceutical active substances, chiefly proteins, such as e.g. antibodies. Human serum albumin (HAS) frequently used in the past, while in fact featuring very good stabilizing and aggregation-inhibiting properties, has in the meantime been found unsuitable because of its potential contamination with blood-borne pathogens. Among previously known polymers, hydroxypropyl-β-cyclodextrin (HP-β-CD) is especially suitable, since it can also be used parenterally in a completely safe way. Further examples are higher-molecular dextrans (18 to 82 kD), PVP, heparin, type A and B gelatins, and hydroxyethyl starch (HES), heparin, dextran sulphate, polyphosphoric acid, poly-L-glutamic acid, poly-L-lysine.
Alongside sugars and polyols, amino acids can also be used in a stabilizing role or in combination with other adjuvants. Amino acids are chiefly used in the stabilization of proteins. For example, addition of histidine, glycine, sodium aspartate (Na-Asp), glutamate, and lysine hydrochloride (Lys-HCl) inhibits the aggregation of rhKGF in 10 mM sodium phosphate buffer (pH 7.0) together with 5% mannitol (Zhang et al., 1995, Biochemistry, 34 (27), 8631-41). Combination of amino acids and propylene glycol, for example, improves the structural stability of rhCNTF (Dix et al., 1995, Pharmaceutical Research (Supplement), 12, S97). Lysine and arginine enhance the thermal stability of IL-1R (Tm enhancement), whereas glycine and alanine have a destabilizing effect (Remmele et al., 1998, Pharmaceutical Research, 15(2), 200-208).
The stability of pharmaceutical active substances can be moreover enhanced through various drying processes. Drying, however, also mostly proceeds in the presence of adjuvants intended to maintain the stability of active substances and to improve the properties of the dry powder. A decisive factor affecting stabilization through drying is immobilization of the active substance in an amorphous matrix. The amorphous state confers high viscosity with low molecular mobility and low reactivity. Advantageous adjuvants must therefore be able to form an amorphous matrix with an as high as possible glass transition temperature wherein the active substance is embedded. Selection of adjuvants therefore particularly depends on their stabilization capabilities. Other factors, such as the pharmaceutical acceptability of the adjuvant, its influence on particle formation, dispersibility, and fluidity, also play an important role, particularly in respect of spray drying processes.
Spray drying constitutes an especially suitable process for enhancement of the chemical and physical stability of peptide-/protein-containing pharmaceutical active substances (Maa et al., 1998, Pharmaceutical Research, 15(5). 768-775). Spray drying is being increasingly used particularly in the field of pulmonary therapy (U.S. Pat. No. 5,626,874; U.S. Pat. No. 5,972,388; Broadhead et al., 1994, J. Pharm. Pharmacol., 46(6), 458-467), since application in an inhaler in the meantime represents a viable alternative in the treatment of systemic diseases (WO 99/07340). A prerequisite is that the particle size of powders should be in the 1-10 μm range, preferably in the 1-7.5 μm range, so that the particles can penetrate into deeper lung segments and thus into the bloodstream. For example, DE-A-179 22 07 describes the production of corresponding spray drying particles. In the meantime, numerous processes for the production of corresponding powders have been described (WO 95/31479; WO 96/09814; WO 96/32096; WO 96/32149; WO 97/41833; WO 97/44013; WO 98/16205; WO 98/31346; WO 99/66903; WO 00/10541; WO 01/13893; Maa et al., 1998, ibid; Vidgren et al., 1987, Int. J. Pharmaceutics, 35, 139-144; Niven et al., 1994, Pharmaceutical Research, 11(8), 1101-1109).
Also suitable as adjuvants are sugars and their alcohols (e.g. trehalose, lactose, saccharose, or mannitol) as well as various polymers (Maa et al., 1997, Pharm. Development and Technology, 2(3), 213-223; Maa et al., 1998, ibid, Adler, 1998, Dissertation University of Erlangen; Costantino et al., 1998, J. Pharm. Sci, 87(11), 1406-1411). The adjuvants chiefly used, however, have various disadvantages. For example, addition of trehalose and mannitol impairs the fluidity of spray drying formulations (C. Bosquillon et al., 2001, Journal of Controlled Release, 70(3), 329-339). At a content of more than 20 weight percent, mannitol additionally tends to recrystallize (Constantino et al., 1998, ibid), with stabilizing effects dramatically decreasing. Lactose, a frequently used adjuvant, while improving the fluidity of spray drying formulations (C. Bosquillon et al., 2001, ibid), raises problems particularly during the formulation of peptide-/protein-containing active substances, since lactose, because of its reducing property, may engage in destabilizing Maillard reactions with peptides/proteins.
During spray drying of antibodies without addition of stabilizers, dehydration, heat, and shearing regularly lead to unfolding of the native secondary structure and thus to dramatic loss of bioactivity. Previously inward facing hydrophobic fractions of the antibody then revert to facing outwards. This progressively occurs on the hydrophobic interfaces between the water droplets generated during spray drying and ambient air. Antibodies in the aqueous phase moreover accumulate to form dimers or higher-order aggregates. Such aggregation is often irreversible. The high temperature at which the proteins are sprayed further represents a critical parameter. The high energy consumption may lead to destabilization of the peptide bonds and to denaturation of the antibody. Aggregation of spray-dried antibodies further occurs during storage of powders. The residual water content of the powder then exerts a particularly adverse effect. Protein aggregates are characterized by reduced or lacking biological activity and reinforced antigenicity.
Multiple sugars described as Coupling Sugars (oligosaccharides) with their principal components of maltosyl sucrose and glucosyl sucrose as well as lactosucrose are used in the food industry. They are used as fillers and dispersants, alongside sweeteners such as aspartame, as moderately sweet components in chewing gums for stabilization of trehalose syrups against crystallizing out, or as so-called NDOs (non-digestible oligosaccharides). Also known is improvement and stabilization of the sweetening quality of asparagyl peptides or the sweet-sour relationship in ballast- and sweetener-containing beverages (US 2003/0059511, EP 1 223 175, DE 199 53 727). Further known from U.S. Pat. No. 5,489,577 and EP 0630 651 is the application of oligosaccharides for stabilization of suspensions produced from therapeutic proteins and fat or oil bases. It is stated that, without premixing with the oligosaccharides during blending and kneading with the hydrophobic, semi-solid masses, the proteins would lose their activity. The stabilization potential over storage, in hydrophilic mixtures or in powders, is not mentioned in any way.
A task of the invention was to propose new adjuvants for the production of pharmaceutical preparations. The corresponding preparations were to be distinguished, inter alia, by good long-term stability.
A further task of the present invention was to provide new adjuvants for the production of dried pharmaceutical preparations. The corresponding pulverulent pharmaceutical preparations were to be distinguished by good long-term stability and, if possible, by inhalability.
A further task of the present invention was to provide novel adjuvants for the production of peptide/protein-containing pharmaceutical formulations, particularly those generated by spray drying. The corresponding peptide/protein-containing pharmaceutical preparations were to be distinguished by good long-term stability and, if possible, by inhalability.
A further task of the present invention was to provide novel adjuvants for the formulation of therapeutic antibodies or antibody derivatives, particularly those generated by spray drying. The corresponding antibody-containing pharmaceutical preparations were again to be distinguished by good long-term stability and, if possible, by inhalability.
A further task of the present invention was to provide corresponding pharmaceutical preparations for application in an inhaler, whether in the form of a dry powder, propellant-containing dosage aerosol, or propellant-free inhalation solution.
The tasks underlying the invention are resolved by the following specifications as well as by the objects/processes represented in the patent claims.